<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{
            display: flex;
            /*flex-direction: row;!*默认：子项目沿着x轴方向从左向右排列*!*/
            /*flex-direction: row-reverse;*/
            /*flex-direction: column;*/
            flex-direction: column-reverse;

            width: 90%;
            height: 600px;
            background-color: skyblue;
        }
        span{
            width: 100px;
            height: 100px;
            background-color: greenyellow;
        }
    </style>
</head>
<body>
<!--flex-direction-->
<div class="">
    <span>1</span>
    <span>2</span>
    <span>3</span>
</div>
</body>
</html>